Vint Cerf Is Working on an Internet for Outer Space

“TCP/IP doesn’t work at interplanetary distances,” 77-year-old Vinton Cerf tells Quanta magazine. “So we designed a set of protocols that do.” Specifically, bundle protocols: a disruption/delay-tolerant networking (DTN) protocol with nodes that can also store information: A data packet traveling from Earth to Jupiter might, for example, go through a relay on Mars, Cerf explained. However, when the packet arrives at the relay, some 40 million miles into the 400-million-mile journey, Mars may not be oriented properly to send the packet on to Jupiter. “Why throw the information away, instead of hanging on to it until Jupiter shows up?” Cerf said. This store-and-forward feature allows bundles to navigate toward their destinations one hop at a time, despite large disruptions and delays… So, a couple decades after conceiving of bundle protocols, is the interplanetary internet up and running? We don’t have to build the whole thing and then hope somebody uses it. We sought to get standards in place, as we have for the internet; offer those standards freely; and then achieve interoperability so that the various spacefaring nations could help each other. We’re taking the next obvious step for multi-mission infrastructure: designing the capability for an interplanetary backbone network. You build what’s needed for the next mission. As spacecraft get built and deployed, they carry the standard protocols that become part of the interplanetary backbone. Then, when they finish their primary scientific mission, they get repurposed as nodes in the backbone network. We accrete an interplanetary backbone over time. In 2004, the Mars rovers were supposed to transmit data back to Earth directly through the deep space network — three big 70-meter antennas in Australia, Spain and California. However, the channel’s available data rate was 28 kilobits per second, which isn’t much. When they turned the radios on, they overheated. They had to back off, which meant less data would come back. That made the scientists grumpy. One of the JPL engineers used prototype software — this is so cool! — to reprogram the rovers and orbiters from hundreds of millions of miles away. We built a small store-and-forward interplanetary internet with essentially three nodes: the rovers on the surface of Mars, the orbiters and the deep space network on Earth. That’s been running ever since. We’ve been refining the design of those protocols, implementing and testing them. The latest protocols are running back-and-forth relays between Earth and the International Space Station… We did another test at the ISS where the astronauts were controlling a little robot vehicle in Germany.